add homeing method

add a static method in the grasp util to home the gripper

include/grasp_util.h

@@ -90,6 +90,13 @@ public:
     bool placeFromAbove(moveit::planning_interface::MoveGroupInterface &move_group, geometry_msgs::Pose &place_pose,
                         double open_amount, std::string supporting_surface_id, std::string object_to_place_id, bool plan_only = false);
 
+    /**
+     * Homes the gripper (in case it was abused before and is in an inconsistent state)
+     * This method is blocking with a maximum runtime of ~30s
+     * @return true if homing succeeded, false otherwise
+     */
+    static bool homeGripper();
+
 };
 
 #endif //PANDA_GRASPING_GRASP_UTIL_H